In the manufacture of ball-socket joints for such applications as the push rods of fuel injector drive train components and cylinder valve drive train components it has, for a long time, been standard practice to ensure that contact between the two socket parts is along a line at a desired location and not at some undesired point. To achieve a precise positioning of the line of contact between the ball and the socket of a ball-socket joint, precise tolerances in the mating surfaces are required and the precise positioning of the line for contact has been achieved by making the socket of a non-spherical shape (i.e., a so-called "gothic arch" or offset radius socket that is machined with a spherical radius that is offset from the radial centerline), while making the ball end part of the joint spherical. An example of such a conventional offset socket ball and socket joint is illustrated in FIG. 1. However, production of such a gothic arch, offset radius, socket requires a machining operation that is twice as difficult as for formation of a spherical socket.
Furthermore, the high compressive loads imposed between the ball and the socket components of such engine sub-system drive trains can result (within as little as 20 to 30 thousand miles) in the metallic surfaces of the ball and/or the socket becoming worn to such an extent that undesirably large amounts of play occur which adversely impact upon the operation of the associated fuel injectors, valves, etc. Thus, when such wear occurs, it is necessary to perform major servicing of the engine and the vehicle equipped with the associated engine must be taken out of use for a day or more.